Carba NP试验及Carba NP-direct试验检测产碳青霉烯酶肠杆菌的临床意义

目的：评价Carba NP试验及Carba NP-direct试验对碳青霉烯类耐药的肠杆菌科细菌碳青霉烯酶检测的临床价值。方法：收集南京医科大学附属无锡市第二人民医院2013年1月至2015年12月临床分离的各种标本耐碳青霉烯类抗生素的肠杆菌科细菌112株,同时选取碳青霉烯敏感的菌株100株作为对照组。所有菌株进行碳青霉烯酶耐药基因PCR检测、改良Hodge试验(MHT试验)、Carba NP试验(CNPt)以及Carba NP-direct(CNPt-d)试验检测。结果：碳青霉烯类耐药的肠杆菌科细菌共112株,92株携带blaKPC-2;8株携带blaNDM-1;1株携带blaVIM-2;1株携带blaIMP-4;10株不携带碳青霉烯酶基因;未检测到携带D组碳青霉烯酶基因的肠杆菌科细菌。以PCR检测的结果为标准,Carba NP试验、Carba NP-direct试验诊断菌株是否产碳青霉烯酶的敏感性和特异性均100%;改良Hodge试验诊断菌株是否产碳青霉烯酶敏感性为96%,特异性为98%。Carba NP试验及Carba NP-direct试验均在2 h内完成检测。结论：Carba NP试验和Carba NP-direct试验均能快速、准确筛查出产碳青霉烯酶的肠杆菌科细菌。Carba NP-direct试验相比Carba NP试验成本低、反应快、结果更明确,可作为表型确认实验和耐药监测的手段。     

质粒介导KPC-2型碳青霉烯酶肺炎克雷伯菌儿童分离株耐药基因研究

目的 研究碳青霉烯类耐药肺炎克雷伯菌临床儿童分离株的耐药特点及分子流行病学特征.方法 收集温州医学院附属第二医院2010年7月-2011年6月从儿童标本中分离的耐碳青霉烯类肺炎克雷伯菌12株,所有菌株为非重复菌株,菌种鉴定采用全自动微生物分析仪.改良的Hodge试验筛选产碳青霉烯酶阳性菌株,采用PCR法检测KPC、IMP、bla(s)、VIM、SPM和整合酶基因,测序确定基因型.对菌株进行质粒结合试验、质粒消除试验检测质粒的转移性.脉冲场凝胶电泳(PFGE)分析耐药菌株的同源性.结果 12株耐碳青霉烯类肺炎克雷伯菌对庆大霉素、妥布霉素、阿米卡星、环丙沙星、左氧氟沙星、复方磺胺甲噁唑的敏感率分别为8.3％、41.7％、58.3％、8.3％、8.3％、33.3％;12株菌均携带有KPC-2基因,且同时携带有TEM-1和SHV型β-内酰胺酶基因,其中SHV-11-like和SHV-1 2-like各6株;11株携带CTX-M型基因,其中4株为CTX-M-14-like基因,6株CTX-M-15-like基因;2株携带有OXA-10型基因,1株携带有PER-1基因.未检出NDM-1、GIM、SPM、SIM、VIM型碳青霉烯酶基因.12株均为Ⅰ类整合酶基因(int1)阳性.2株通过接合试验把质粒传递给受体菌EC600.所有接合子blaTEM-1基因阳性、超广谱β-内酰胺酶(ESBL)基因阳性及对亚胺培南、庆大霉素、阿米卡星、妥布霉素和头孢噻肟耐药,接合子ESBL基因型与供菌一致.2株菌经质粒消除后对亚胺培南的MIC值均有较大程度降低,消除后KPC-2基因扩增为阴性.12株KPC-2基因阳性菌株经PFGE分成5个基因型,主要为B型和C型.结论 KPC-2型碳青霉烯酶基因已经在儿童肺炎克雷伯菌中播散,常伴随携带多种类型的ESBL基因和Ⅰ类整合酶基因,部分耐药基因可通过质粒播散.     

头孢他啶/阿维巴坦对耐碳青霉烯类肺炎克雷伯菌的体外抗菌活性研究

目的 研究头孢他啶/阿维巴坦(CZA)对耐碳青霉烯类肺炎克雷伯菌(CRKP)的体外抗菌活性并检测其相关耐药基因,为临床治疗CRKP提供参考依据.方法 选取2017年1月至2019年12月北京中医药大学东方医院临床分离的257株CRKP菌株,应用VITEK MS微生物质谱仪和VITEK-2 Compact微生物药敏分析仪进行菌种鉴定和药敏分析,用K-B法检测CZA的药物敏感性.采用碳青霉烯酶抑制剂增强试验对CRKP菌株进行产酶表型检测.通过NG-Test CARBA 5对耐CZA的CRKP菌株进行相关耐药基因检测.结果 257株CRKP菌株对CZA的耐药率为7.8％,对哌拉西林/他唑巴坦、阿莫西林/克拉维酸、头孢哌酮/舒巴坦、头孢呋辛、头孢他啶、头孢曲松、头孢西丁的耐药率均为100％,头孢吡肟97.2％、左氧氟沙星97.1％、阿米卡星48.5％、庆大霉素76.4％、复方新诺明46.5％、替加环素35.5％.碳青霉烯酶抑制剂增强试验结果显示,CRKP菌株耐药主要以产丝氨酸酶为主.20株耐CZA的CRKP菌株中,产KPC 11株,产OXA-481株,产IMP 1株,产NDM 4株,既产KPC又产NDM 2株,不产碳青霉烯酶1株.结论 CZA对CRKP菌株有较强的抗菌效果,抗菌活性明显优于临床常用抗菌药物.CZA体外药敏试验可在临床常规开展,为临床治疗CRKP提供更多的参考.     

老年人亚胺培南耐药铜绿假单胞菌耐药性研究

目的 明确我院老年病人临床分离铜绿假单胞菌的耐药性、同源性及耐碳青霉烯菌株的基因型。方法 收集我院2006年5月-2009年5月自临床老年病人分离的262株铜绿假单胞菌,纸片扩散法测定其对16种抗菌药物的耐药性;琼脂稀释法和E test法测定耐碳青霉烯菌株对14种抗菌药物的MIC值,PCR扩增及克隆测序分析金属酶基因型。脉冲场凝胶电泳(PFGE)分析携带金属酶基因型菌株的同源性。结果 262株铜绿假单胞菌中筛选到104株耐碳青霉烯。104株耐碳青霉烯铜绿假单胞菌对氨苄西林/舒巴坦、头孢哌酮/舒巴坦两个含舒巴坦制剂药物耐药率分别为78.9％和35.9％,对多黏菌素E耐药率最低为6.0％,对米诺环素耐药率58.3％,其余抗菌药物耐药率均大于70.0％;104株亚胺培南耐药铜绿假单胞菌中12株携带金属酶基因,10株检测到有携带VIM-2基因的1类整合子。PFGE分型中12株菌株属于5个克隆株。结论 在我院流行的亚胺培南耐药铜绿假单胞菌中,金属酶基因不是最主要的基因型,金属β-内酰胺酶均为VIM-2型金属酶,耐药基因盒分布于不同的1类整合子中,整合子播散是最主要的流行方式。     

一株产碳青霉烯酶IMP-26阴沟肠杆菌的分离鉴定

在过去的几年中,产碳青霉烯酶的肠杆菌科细菌不断被发现,这引起了临床工作者的强烈担忧.我院发现一株碳青霉烯类抗菌药物耐药的阴沟肠杆菌,此临床菌株分离自一位9个月的哮喘患儿,对亚胺培南和厄他培南表现为耐药,其最低抑菌浓度分别为4 μg/ml和16μg／ml.对青霉素类,头孢类及头孢与酶的复合制剂都表现为耐药.进一步的实验显示此菌株的Hodge试验阳性,确定该菌株产碳青霉烯酶.通过对亚胺培南与亚胺培南+EDTA的纸片的抑菌圈直径的比较,发现此种碳青霉烯酶能被EDTA抑制.通过PCR扩增,发现此阴沟肠杆菌含有blaInt11、blaIMP和blaTEM基因,通过测序和比对确定blaIMr的基因型为blaIMP-26,balTEM基因的基因型为blaTEM-104.通过等电聚焦电泳,也证实此阴沟肠杆菌产IMP和TEM酶.     

儿科对碳青霉烯类耐药铜绿假单胞菌产金属酶的研究

目的 了解目前儿科对碳青霉烯类抗生素耐药铜绿假单胞菌产金属酶的情况。方法 本研究收集了2003年12月至2005年11月，北京儿童医院住院患儿中分离出对碳青霉烯类抗生素耐药的铜绿假单胞菌59株。使用E试验法检测金属酶的耐药表型，PCR技术检测编码金属酶的IMP、VIM、SPM和GIM4种基因型。结果 本研究59株对碳青霉烯类抗生素耐药铜绿假单胞菌中，29株金属酶耐药表型结果阳性，占49．2％。39株金属酶基因型阳性，占66．1％，其中扩增出IMP型阳性35株，占89．7％，VIM型阳性4株，占10．3％。未检测出SPM和GIM型金属酶。对哌拉西林、哌拉西林-他唑巴坦产金属酶不敏感率高于非产金属酶菌株，差异有统计学意义（P〈0．05）。对产金属酶菌株β-内酰胺类抗生素头孢噻肟、头孢哌酮、头孢他啶、头孢吡肟、头孢哌酮-舒巴坦的MIC90均达到256μg／ml，MIC90均大于256μg／ml，高于非产金属酶菌株。结论 从本研究分离的菌株显示儿科铜绿假单胞菌产金属酶率高于成人报道，产金属酶是儿科分离对碳青霉烯类抗生素耐药铜绿假单胞菌的重要耐药机制。且以产IMP型金属酶为主，少部分产VIM型金属酶。产金属酶菌株对β-内酰胺类抗生素耐药比非产金属酶菌株更严重，尤其对哌拉西林和哌拉西林-他唑巴坦耐药性高。E试验法易用于铜绿假单胞菌产金属酶的初步筛选，但不能单独作为检测铜绿假单胞菌产生金属酶的确证性试验。     

鲍曼不动杆菌对碳青霉烯类抗生素的耐药分析及基因型研究

目的分析20株鲍曼不动杆菌对耐碳青霉烯类抗生素的耐药性及对碳青霉烯酶基因的研究。方法用API鉴定条进行细菌鉴定及K-B法进行药敏试验,用碳青霉烯酶4种基因的特异性引物进行聚合酶链反应（PCR）扩增和基因型的测序分析,并通过网上Genbank进行比对以确定编码酶基因的类型。结果 20株鲍曼不动杆菌对左旋氧氟沙星、丁胺卡那霉素、多粘菌素B的耐药率分别为50%、25%、4%。其它抗生素的耐药率均在90%以上。携带D类碳青霉烯酶OXA-23基因有17株（85%）,携带OXA-51基因有15株（75%）,OXA-24、OXA-58基因引物PCR扩增为阴性,随机各抽取3株OXA-23基因阳性株进行测序后通过在网上Genbank比对发现与OXA-23标准株99%同源,OXA-51基因阳性株与OXA-51标准株98%同源。结论本院耐碳青霉烯类抗生素的鲍曼不动杆菌对多粘菌素B的耐药率最低,其次是丁胺卡那霉素,以携带OXA-23型碳青霉烯酶基因为主,应引起临床高度重视,防止在院内广泛传播。     

对碳青霉烯类抗生素敏感性下降的肠杆菌科细菌耐药机制的研究及流行病学调查

目的 对临床分离的碳青霉烯类抗生素耐药的肠杆菌科细菌进行耐药机制研究及流行病学调查.方法 收集2010年1月至2010年8月,对碳青霉烯类抗生素敏感性下降的肠杆菌科细菌18株,全自动微生物鉴定仪检测细菌对常见抗生素最低抑菌浓度(MIC),纸片法检测细菌产超广谱β-内酰胺酶、头孢菌素酶、碳青霉烯酶的情况,并用PCR扩增、DNA测序确定所产碳青霉烯酶基因型.脉冲场凝胶电泳对耐药菌进行同源性分析.结果 8株耐药菌全部检出ESBLs酶、AmpC酶,17株检出KPC-2酶,3株EDTA纸片法阳性提示产其他金属碳青霉烯酶,其中两株合并产KPC-2.脉冲场凝胶电泳结果显示15株肺炎克雷伯菌分为6种带型.结论 KPC-2碳青霉烯酶是造成肠杆菌科细菌对碳青霉烯类抗生素敏感性下降的主要原因,并在我院局部短暂流行,携带KPC-2基因的临床菌株同时携带多种耐药基因.     

医院泛耐药鲍曼不动杆菌对碳青霉烯抗生素的耐药机制

目的 探讨医院泛耐药鲍曼不动杆菌对碳青霉烯抗生素的耐药机制.方法 应用PCR方法对2010年12月至2012年3月期间本院从临床痰标本中分离的36株泛耐药鲍曼不动杆菌进行碳青霉烯酶IMP、OXA23基因和整合子基因检测;提取细菌膜蛋白行SDS-PAGE电泳分析其组成.结果 36株泛耐药鲍曼不动杆菌碳青霉烯酶OXA23基因扩增均为阳性;14株碳青霉烯酶IMP基因扩增阳性,22株阴性.12株整合子PCR产物约1200 bp,10株约3000 bp,14株整合子PCR产物约3500 bp.与碳青霉烯抗生素敏感鲍曼不动杆菌膜蛋白比较,22株泛耐药鲍曼不动杆菌存在相对分子质量为25 000、36 000的膜蛋白缺失.结论 医院泛耐药鲍曼不动杆菌耐碳青霉烯抗生素机制与产IMP、OXA23碳青霉烯酶及膜蛋白缺失有关.     

肺炎克雷伯菌AmpC酶检测及抗生素选择

目的 调查济宁市第一人民医院肺炎克雷伯菌质粒介导AmpC酶表型及其对常用抗生素的耐药性,为临床用药提供依据。方法 收集2017年1月~7月济宁市第一人民医院临床分离的非重复肺炎克雷伯菌97株,应用头孢西丁纸片扩散法进行肺炎克雷伯菌AmpC酶表型初筛,对初筛阳性菌用多重PCR方法检测质粒介导AmpC酶基因,分析其耐药情况。结果 97株肺炎克雷伯菌中共筛选出40株对头孢西丁不敏感菌株,经多重PCR扩增,有7株AmpC酶阳性,检出率为7.22%（7/97）,均为DHA型。产质粒介导AmpC酶菌株仅对亚胺培南敏感（100.00%）。结论 济宁市第一人民医院产质粒介导AmpC酶肺炎克雷伯菌发生率相对较低,以DHA型基因为主,治疗应首选碳青霉烯类抗菌药物。     

VIM and IMP metallo-β-lactamases and other extended-spectrum β-lactamases in Escherichia coli and Klebsiella pneumoniae from environmental samples in a Tunisian hospital

An extremely drug-resistant Enterobacteriaceae species emerged in Kasserine Hospital, Tunisia between 2009 and 2010 causing a local outbreak. We aimed to characterize extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL)-producing Enterobacteriaceae from the hospital environment. Swabs were collected from ten different wards from Kasserine Hospital, Tunisia. A total of 46 isolates were cultured onto MacConkey agar supplemented with ceftazidime to select for ESBL-producing Enterobacteriaceae. Identification and susceptibility patterns were performed using Phoenix-automated phenotypic identification criteria. Extended spectrum β-lactamases (ESBLs) were detected using cefepime ESBL E-test. Colony blotting was first used to detect the occurrence of bla(SHV) , bla(CTX-M) , bla(CMY) , bla(IMP) , and bla(VIM) genes. PCR was used to amplify these genes, and the amplicons were sequenced and analyzed. Total DNA was digested with XbaI, and PFGE was used to type the major isolates that produced IMP-1. Among the 46 isolates, 63% were Klebsiella pneumoniae, 13% were Escherichia coli, 8.7% were Proteus mirabilis, 6% were Enterobacter cloaceae, 4.3% were Providencia rettgeri, 2.5% were Serratia marcescens, and 2.5% were Pantoea agglomerans. PCR amplification and DNA sequencing showed that hospital environment isolates produced SHV-125, CTX-M-15, CMY-2 ESBLs, and IMP-1 and VIM-2 MBLs. PFGE typing showed the emergence of IMP-1 MBL-producing K. pneumoniae isolates that were not clonal. In this study, we report the first characterization of IMP-1 and VIM-2 MBL-producing K. pneumoniae and E. coli isolates collected from Kasserine Hospital, Tunisia.     

Specific detection of blaVIM and blaIMP metallo-β-lactamase genes in a single real-time PCR

This study describes the development of a real-time PCR protocol for rapid detection of the most common bla(VIM) (bla(VIM-1), bla(VIM-2), bla(VIM-3), bla(VIM-4), bla(VIM-5), bla(VIM-6), bla(VIM-10), bla(VIM-11), bla(VIM-12)) and bla(IMP) (bla(IMP-1), bla(IMP-2), bla(IMP-6), bla(IMP-8), bla(IMP-10), bla(IMP-15), bla(IMP-19), bla(IMP-20)) genes in a single reaction. The genes were specifically detected and clearly differentiated into four groups, i.e., (i) bla(VIM-1)-like (bla(VIM-1), bla(VIM-4), bla(VIM-5), bla(VIM-12)); (ii) bla(VIM-2)-like (bla(VIM-2), bla(VIM-3), bla(VIM-6), bla(VIM-10), bla(VIM-11)); (iii) bla(IMP-1)-like (bla(IMP-1), bla(IMP-6), bla(IMP-10)); and (iv) bla(IMP-2)-like (bla(IMP-2), bla(IMP-8), bla(IMP-15), bla(IMP-19), bla(IMP-20)), by melting curve analysis of the real-time PCR products. The protocol was used to screen positive bla(VIM-1), bla(VIM-2) and bla(IMP-1) control strains, 70 Gram-negative isolates resistant to carbapenems, and 30 Gram-negative isolates susceptible to carbapenems (negative controls).     

IMPs, VIMs and SPMs: the diversity of metallo-β-lactamases produced by carbapenem-resistant Pseudomonas aeruginosa in a Brazilian hospital

Pseudomonas aeruginosa isolates (n=183), collected from bacteraemic patients hospitalised in Sao Paulo Hospital (Brazil) during 2000-2001, were screened for susceptibility to antimicrobial agents. The polymyxins were the most active compounds (100% susceptibility), followed by amikacin and cefepime (59.0%), meropenem (57.4%), and imipenem and gentamicin (55.2%). Imipenem-resistant isolates were ribotyped and screened for production of metallo-beta-lactamases (MBLs) by PCR with primers for bla(IMP), bla(VIM) and bla(SPM). MBL production was detected in 36 isolates (19.7% of the entire collection; 43.9% of the imipenem-resistant isolates) and the MBLs included SPM-1-like (55.6%), VIM-2-like (30.6%) and IMP-1-like (8.3%) enzymes.     

Dissemination of metallo‐β‐lactamase in Pseudomonas aeruginosa isolates in Egypt: mutation in blaVIM‐4

This study was designed to investigate the prevalence of metallo‐β‐lactamase (MBL) in Pseudomonas aeruginosa isolates collected from Suez Canal University Hospital in Ismailia, Egypt. Antibiotic susceptibility testing and phenotypic and genotypic screening for MBLs were performed on 147 isolates of P. aeruginosa. MICs were determined by agar dilution method for carbapenem that was ≥2 μg/mL for meropenem. MBL genes were detected by multiplex and monoplex PCR for P. aeruginosa‐harbored plasmids. Mutation profile of sequenced MBL genes was screened using online software Clustal Omega. Out of 147 P. aeruginosa, 39 (26.5%) were carbapenem‐resistant isolates and 25 (64%) were confirmed to be positive for MBLs. The susceptibility rate of P. aeruginosa toward polymyxin B and norfloxacin was 99% and 88%, respectively. Identification of collected isolates by API analysis and constructed phylogenetic tree of 16S rRNA showed that the isolates were related to P. aeruginosa species. The frequency of blaGIM‐1, blaSIM‐1, and blaSPM‐1 was 52%, 48%, and 24%, respectively. BlaVIM and blaIMP‐like genes were 20% and 4% and the sequences confirm the isolate to be blaVIM‐1, blaVIM‐2, blaVIM‐4, and blaIMP‐1. Three mutations were identified in blaVIM‐4 gene. Our study emphasizes the high occurrence of multidrug‐resistant P. aeruginosa‐producing MBL enzymes.     

Evaluation of Double-Disk Potentiation and Disk Potentiation Tests Using Dipicolinic Acid for Detection of Metallo-β-Lactamase-Producing Pseudomonas spp. and Acinetobacter spp

Accurate detection of metallo-β-lactamase (MBL)-producing Pseudomonas spp. and Acinetobacter spp. became very important with the increasing prevalence of carbapenem-nonsusceptible clinical isolates. The performance of phenotypic MBL detection methods may depend on the types of MBL and the characteristics of the isolates. A high false-positive rate is a problem with EDTA-based MBL detection methods. We evaluated the performance of double-disk potentiation tests (DDPTs) and disk potentiation tests (DPTs) with dipicolinic acid (DPA) using 44 isolates of Pseudomonas spp. and Acinetobacter spp. producing IMP-1-like, VIM-2-like, and SIM-1 type MBLs. Also, we characterized P. aeruginosa isolates with positive imipenem (IPM)-DPA DDPT, but negative meropenem (MEM)-DPA DDPT, and determined possibility of improving a DDPT by using MacConkey agar. Among five different DDPT methods, the IPM-DPA 250-μg method showed the highest sensitivity (97.7%) and specificity (100%). Among four DPT tests, the highest sensitivity (100%) was shown by the IPM-EDTA 1,900-μg disk method, but the specificity was very low (11.4%). Five of six P. aeruginosa isolates with false-negative DDPTs with MEM-DPA 250-μg disks carried bla(IMP-6,) and the high level resistance to MEM (MIC ≥ 512 μg/ml) was reduced by the presence of phenylalanine arginine β-naphtylamide. Improvement of DDPTs was observed when MacConkey agar was used instead of Mueller-Hinton agar. In conclusion, DPA is a better MBL inhibitor than EDTA for detection of Pseudomonas spp. and Acinetobacter spp. with IMP-1-like, VIM-2-like, and SIM-1-type MBLs. In DPA DDPTs, IPM disks perform better than MEM disks when the isolates are highly resistant to MEM due to the overexpression of efflux pumps.     

Convenient test using a combination of chelating agents for detection of metallo-beta-lactamases in the clinical laboratory

Although transmissible metallo-beta-lactamases (MBLs) are a serious threat to beta-lactam antibiotic therapy, the CLSI currently does not recommend testing methods for the detection of MBLs. The aim of this study was to evaluate the capability of double-disk tests (DDTs) by using disks containing a combination of the chelators 2-mercaptopropionic acid (MPA) and Tris-EDTA (TE) to detect MBLs. Sixteen isolates (4 Acinetobacter baumannii isolates, 6 Pseudomonas aeruginosa isolates, 1 Serratia marcescens isolate, 1 Aeromonas hydrophila isolate, 1 Aeromonas veronii isolate, 2 Chryseobacterium meningosepticum isolates, and 1 Stenotrophomonas maltophilia isolate) producing IMP-1, IMP-1-like, IMP-18, GIM-1, SPM-1, VIM-2, VIM-2-like, and chromosomal MBLs and 20 isolates (7 Klebsiella pneumoniae isolates, 3 Escherichia coli isolates, 5 Enterobacter cloacae isolates, 2 S. marcescens isolates, 1 Proteus mirabilis isolate, and 2 A. baumannii isolates) producing non-MBL carbapenemases, AmpC beta-lactamases, and extended-spectrum beta-lactamases were tested. The DDT method was evaluated by using four types of chelator disks (TE, high-strength TE, MPA, and TE plus 20 microl of MPA [at various concentrations]) and the beta-lactams imipenem (IPM), meropenem (MEM), ertapenem (ERT), and ceftazidime (CAZ). DDTs with IPM and a TE disk supplemented with 1:320 MPA detected all MBLs and yielded no false-positive results. Some, but not all, MBL producers were detected in IPM-based tests involving the single chelator TE or MPA alone or by ERT- or CAZ-based tests. IPM-based tests with MPA concentrations other than 1:320 and all MEM-based tests had suboptimal sensitivities or specificities. DDT with IPM and a TE disk supplemented with 20 microl of 1:320 MPA appears to be convenient for the detection of MBLs in the clinical laboratory.     

洋葱伯克霍尔德菌耐药性和金属β-内酰胺酶的检测

目的探讨洋葱伯克霍尔德菌耐药情况及其多重耐药特点。方法用微量琼脂稀释法检测2004年1月至2006年12月临床分离不重复75株洋葱伯克霍尔德菌对15种抗菌药物的抗菌活性及其产金属β-内酰胺酶情况，比较产酶株与非产酶株抗药活性。结果2004—2006年洋葱伯克霍尔德菌检出率呈上升趋势，痰标本分离率较高。感染者分布于临床各个科室，并患有各种严重基础疾病，并使用过抗菌药物。葱伯克霍尔德菌对多数抗菌药物耐药，仅对复方新喏明、美罗培南、头孢哌酮／舒巴坦、哌拉西林／他巴唑坦敏感，敏感率分别为95％、82．8％、74．7％、70．7％；而对头孢噻肟、头孢哌酮、头孢曲松、阿米卡星、氨曲南、哌拉西林耐药率超过50％。产金属β-内酰胺酶株与非产金属β-内酰胺酶株比较，产酶株对含酶抑制剂β-内酰胺类抗生素敏感性较高。结论洋葱伯克霍尔德菌对多数抗菌药物耐药，仅对复方新喏明、头孢哌酮／舒巴坦、美罗培南、哌拉西林／他巴唑坦敏感．建议临床医生根据药敏试验合理用药，以减少耐药菌株的产生。     

Molecular epidemiology of clinical Pseudomonas aeruginosa isolates carrying IMP-1 metallo-beta-lactamase gene in a University Hospital in Turkey

Pseudomonas aeruginosa isolates carrying IMP- or VIM-type metallo-beta-lactamase (MBL) have been increasingly reported in hospitals worldwide. One hundred P. aeruginosa clinical isolates from unrelated inpatients hospitalized at a Turkish university hospital were screened for the presence of bla(IMP) and bla(VIM) genes by polymerase chain reaction (PCR). One (1%) isolate was found to carry a VIM-type MBL gene, whereas nine (9%) carried an IMP-1 MBL gene carried on a cassette inserted into a class 1 integron. Only four of the IMP producers were detected as MBL producers according to E-test MBL. Minimum inhibitory concentrations (MICs) of imipenem for the IMP-1 and VIM-type MBL-producers were highly variable (MIC values, 8-128 mug/ml). Imipenem resistance was not plasmid-mediated according to the transformation assays. Piperacillin/tazobactam was the only effective drug in antimicrobial susceptibility testing. No aztreonam-resistant IMP and VIM producers were detected to produce an extended-spectrum beta-lactamase (ESBL). Three class 1 integrons of approximately 2,300 bp, 1,800 bp, and 1,500 bp in size were detected in each of the nine IMP-positive isolates. Sequencing revealed three novel gene cassette arrays, aac(3)-1c-cmlA5, bla(IMP-1)-aadA7-like, and aacA7-smr-2-orfD. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) indicated that a clonal spread of IMP-1-producers had occurred in this hospital.     

Metallo-β-lactamase-producing Enterobacteriaceae isolates at a Taiwanese hospital: lack of distinctive phenotypes for screening

We investigated the prevalence of metallo-β-lactamases (MBLs) among 1,827 Enterobacteriaceae isolates collected in 2006 and evaluated the VITEK 2 microbiology system, modified Hodge test, and 2 combined disk tests as the screening tools for MBLs by using these isolates and 77 previously characterized IMP-8 producers. The IMP-8 MBL was identified in 18 isolates of 2006, and the IMP-8-positive isolates represented 0.2%, 1.1%, and 5.0% of all Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae isolates, respectively. Only one-third of all MBL producers could be recognized by either VITEK 2 or the Hodge test. MBL production could be identified in 38 (40%) of the 95 IMP-8-producing isolates by the combined disk test using meropenem disks supplemented by phenylboronic acid and EDTA, and only 2 (2.1%) isolates gave positive results in the combined disk test using meropenem disks supplemented with dipicolinic acid. Of all IMP-8 producers, 37.9%, 50.5%, and 32.6% were nonsusceptible to tigecycline, fluoroquinolones, and both, respectively. In conclusion, this study demonstrated the lack of distinct phenotypes that could be easily identified among the IMP-8-producing Enterobacteriaceae isolates at a Taiwanese hospital. Continuous surveillance and monitoring are needed because the widespread of tigecycline- and fluoroquinolone-coresistant MBL producers may become a serious therapeutic problem.     

Emergence of Pseudomonas aeruginosa strains producing metallo-β-lactamases of the IMP-15 and VIM-2 types in Mexico

Eighty-six carbapenem non-susceptible Pseudomonas aeruginosa isolates collected in the National Institute of Respiratory Diseases of Mexico City were screened for the presence of metallo-β-lactamase (MBL) activity using both E-test strips and a microbiological assay with EDTA-imipenem. Genomic comparisons and sequence analyses conducted with these isolates revealed the presence of bla_VIM-2 in two clonally related isolates, and bla_IMP-15 in a clonally unrelated isolate. Both genes were found to be carried by class 1 integrons, and bla_IMP-15 was additionally present on a broad host-range plasmid. This is the first report of co-existing P. aeruginosa strains producing different MBLs in a Mexican hospital, highlighting the necessity of appropriate surveillance to prevent dissemination of carbapenem resistance.